package com.itheima.day10;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

public class Practice2 {
    public static void main(String[] args) {
        HashMap<String, Integer> map = new HashMap<>();
        map.put("老王", 18);
        map.put("小张", 20);
        map.put("老王", 20);
        System.out.println(map.size());
        ArrayList list = new ArrayList();
        ArrayList list1 = new ArrayList();
        ArrayList list12 = new ArrayList<>();
        Map<String, Integer> map1 = new HashMap<String, Integer>();
    }
}
